This response best fits with the prompt and the "help" tips, which ask you to use the substr, rand, and strlen functions.
The prompt asks you to print a random letter from your name. The string, then, is your name. We need a substring of that, to get just one letter.
So, we know we need to echo/print substr.
A substring needs to know which string you're taking from (in this case, your name), where you want to start taking within the string, and how many characters to return.
We know the string we're taking from (our name) and how many characters we need (just 1 letter). So, where do we start within the string? That's where random and stringlength functions come in.
We're telling the substring that we're pulling randomly within the string, but the random function needs to know where to start and where to end. We're telling it to start at 0 in the array, or the first letter in our name/string. We're telling it to end at the last letter, using the stringlength function; but, because it's an array, the last letter in our name/string is represented as -1.
So, we get print substr($name,rand(0,strlen($name) - 1),1);
I hope this clarifies how this works (typing it out sure helped me understand). Thanks, chippro!